Detect Lovelace resource type based on file extension

[spacegaier]

Breaking change

Proposed change

Automatically detect the resource type based on the extension. Initially we now start with an empty dropdown. As long as it is empty and as soon as an URL is inserted we will check for extensions "js" and "css" to automatically determine the type.

One the dropdown has a value we no longer update it, even if the URL is changed, but the user can still manually change/override the selection.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (thank you!)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example configuration

Additional information

• This PR fixes or closes issue: fixes Resources: automatically change resource type dropdown depending on file extension #5164
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

[spacegaier]

The fact that we currently allow duplicate URLs is something the backend should correct I guess.